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Dimensions of Dental Hygiene is committed to the highest standards of professionalism, accuracy and integrity in our mission of education supporting oral health care professionals and those allied with the dental industry. Through our print and digital media platforms, continuing education activities, and events, we strive to deliver relevant, cutting-edge information designed to support the highest level of oral health care.

The views expressed in this article are those of the authors and do not reflect the official
policy of the United States Air Force, the US Department of Defense, or the US Government.

Digital radiography is an integral part of effective
diagnosis and treatment of oral diseases.
Normal anatomical structures, however, may sometimes mimic
pathology on radiographs. Many areas of the oral cavity can suggest
that a serious problem exists once radiographed. Oral health professionals
need to refresh their anatomy knowledge and diagnostic
skills to adeptly evaluate radiographs.

INCISIVE FOSSA

The incisive fossa—an area of thin bone located near the maxillary lateral incisors—is one of the most common anatomical appearances on radiographs that may mimic a disease process. The incisive fossa presents as a decreased radiopacity of bone surrounding the lateral incisor roots. Frequently, the soft tissue of the nose is superimposed over or apical to the apex of the lateral incisor root, making the fossa appear more radiolucent than surrounding bone (Figure 1).1

FIGURE 1. These periapical
radiographs show the incisive
fossa (circled in yellow) as a
diffuse radiolucent area
around the root of the right
lateral incisor (#7) with the
ala (wing) of the nose (green
line) superimposed over the
apex of the lateral incisor.
Note the lamina dura and
periodontal ligament space
are intact around the entire
root, indicating normal
anatomy.

FIGURE 2. Anterior
periapical radiographs
showing a well-localized
radiolucent
area at the apex of the
right lateral incisor
(#7). Note that the
radiolucent area is
continuous with the
lamina dura and
periodontal ligament
space on both images,
indicating loss of bone
due to tooth origin.

Ensuring this radiolucent area is normal anatomy necessitates careful evaluation of the periodontal ligament space and lamina dura around the lateral incisor root. If both are intact around the entire tooth, the diffuse radiolucent area is the incisive fossa. If there is a break in the lamina dura and/or periodontal ligament space that is continuous with a well-defined radiolucent area, a disease process associated with the tooth is likely (Figure 2). Further tests are recommended.

ANTERIOR MANDIBLE

The anterior mandible area is thin facial-lingually and may present radiographically as a diffuse radiolucent area that is more evident on intraoral radiographs (Figure 3A to Figure 3B). Careful evaluation of the lamina dura and periodontal ligament space of the incisor roots will help determine if the anatomy is normal (Figure 4).1

FIGURE 3A. These anterior periapical radiographs show increased radiolucent
bone around the roots of the incisors due to thin facial-lingual bone width
(circled in yellow).

FIGURE 3B. On the left, the anterior periapical area
shows intact periodontal ligament space and lamina
dura. The right radiograph, made with less time to
purposely underexpose the area, shows bone evident
in the radiolucent area.

FIGURE 4. These periapical radiographs of a
well-defined radiolucent area with loss of
the lamina dura surrounding the right
central incisor (#25) indicate bone loss, most
likely due to tooth origin.

MENTAL FORAMEN

The mental foramen is an opening of the mandibular canal on the facial aspect of the mandible. It appears as a round-to-ovoid, radiolucent entity (Figure 5). In some pa­tients, the mental foramen will be superimposed over the root of the second premolar and may mimic pathosis. Evaluation of the lamina dura and periodontal ligament space is crucial for correct interpretation.1

SALIVARY GLAND

The submandibular salivary gland depression is a normal anatomical landmark where the mandible narrows facial-lingually inferior to the mandibular molars. It accommodates the submandibular salivary gland. Presenting as a well-localized, radiolucent area apical to the man­dibular molars and inferior to the lower border of the mandible (Figure 6), this depression does not have a well-defined appearance.1 On a pantomograph, the area may appear more radiolucent due to adjacent radiopaque areas created by the imaging. Superiorly, a diffuse, radiopaque area, which is the ghost image of the opposite ramus, is visible, and in the anterior midline of the pantomograph is the superimposition of the cervical spine (Figure 7). This appearance is within the range of normal.2

FIGURE 5. The stone should be moved from the
90° position to the 110° (or 1 o'clock) position
when held on the right side.

FIGURE 6. The well-localized radiolucent area of the submandibular salivary
gland depression (yellow triangle) is seen in these periapical radiographs. The
thick radiopaque superior border is the mylohyoid ridge.

FIGURE 7. This
pantomograph
shows a prominent
left submandibular salivary
gland depression
as a diffuse
radiolucent area
(circled in yellow).
Superimposition of
the cervical spine
(pink shaded area) and the ghost image of the opposite ramus (green shaded
area) present as more radiopaque areas, making the radiolucent
submandibular salivary gland depression more evident.

AIRWAY

The airway is generally seen on pantomographs that are superimposed over the ramus of the mandible (Figure 8A to Figure 8C). Sometimes, the airway appears radiolucent, causing the angle of the mandible to look "burned out." This indicates that no information was captured. Burn out should not be confused with pathosis or mandibular fracture. To correct this, another pantomograph should be made using a lower peak kilovoltage (kVp) and milliamperage (mA) setting—purposely underexposing the patient to produce a lighter image (Figure 8B).2 In pantomographic imaging, saturation can caused by overexposure, but is most likely due to a gamma correction setting in the software.

FIGURE 8A. The
airway is
superimposed as a
radiolucent band
over the right and
left ramus of the
mandible (yellow
arrows) in this
pantomograph.

FIGURE 8B. This
pantomograph is
lightened to show
the intact
mandible in the
area of the
superimposed
airway.

FIGURE 8C. The
superimposed
airway is visible in
this pantomograph.

CERVICAL SPINE

Occasionally, the cervical spine is seen on the lateral aspects of the pantomographs, due to technique error. In most cases, the cervical spine is curved, and the anterior arch of the atlas (C1) is superimposed on the condylar neck—giving the impression of an increased radiopacity within the upper aspect of the posterior ramus and neck of the condyle (Figure 9). The best way to avoid this is to ensure proper positioning and use of correct technique. Oral health professionals should ask patients to stand tall and tuck their chins slightly downward. This will help to straighten the cervical spine and prevent the atlas (C1) from superimposing on the ramus.

SETTING ADJUSTMENT

Advanced technology in direct digital pantomographic imaging gives clinicians the opportunity to change settings to match the size and shape of patients' jaws. For example, when imaging a small/average woman, it may be appropriate to reduce the breadth of the posterior focal trough to a size consistent with most adolescents. The tips discussed previously help to prevent capturing the cervical spine in the image. If appearing in the pantomograph, the cervical spine should be straight without superimposing the mandible.

ANOMALY OF THE SPINE

The best way to evaluate a spine is to find the anterior arch of the atlas and start by counting, C1 (Figure 9). Separation between C1 and C2 cannot be seen because the odontoid process of C2 is superimposed by the transverse processes of C1 as the dens of C2 projects upward. Next, follow the outline of the bone, and look for discontinuity in the thin, cortical outline of the vertebra, including end plates. The vertebral disc lies within the spaces between the end plates, but the vertebral disc cannot be seen on pantomographic images. Sometimes, in the area of C2 to C3 or C3 to C4, the endplates have fused and the disc space isn't visualized. When fusion of the vertebral end plates is seen, a referral to a medical provider is suggested to rule out a congenital anomaly.

FIGURE 9. Anterior
arch of the atlas is
superimposed on
the ramus and
condylar neck,
bilaterally.

FIGURE 10. The
transverse foramen
contains the
vertebral artery,
which is commonly
mistaken for
pathology.

VERTEBRAL ARTERY

In all panoramic images, clinicians should be aware of the canals of the vertebral artery. They bilaterally and vertically ascend through the transverse foramina of the vertebral bodies before turning to enter the foramen magnum. This artery is a great mimicker of pathology, such as multiple myeloma with its round, well defined, almost punched out appearing radiolucency in the cervical spine, usually seen at the C2 to C3 level (Figure 10).

CONCLUSION

Dental professionals are committed to ensuring the oral health of their patients, which includes taking and examining digital radiographs that may sometimes depict anatomical structures mimicking pathology. Clinicians must remain current on their knowledge of anatomy to ensure correct interpretations of such imaging.

MITZI J. PALAZZOLO, DDS, MS, Capt, USAF, DC, is a staff member in the Department of
Oral and Maxillofacial Pathology in the 59th Dental Training Squadron and an associate professor at the
Uniformed Services University of the Health Sciences. She is also a diplomate of the Board of Oral and
Maxillofacial Pathology, and a fellow of the American Academy of Oral and Maxillofacial Pathology.

TERESA REEVES, DDS, JD, Lt Col, USAF, DC, is the director of dental processing,
59th Group Radiology Officer, and an assistant professor of oral and maxillofacial radiology in the Air
Force Postgraduate Dental School, the Uniformed Services University of the Health Sciences. She is
also a diplomate of the American Board of Oral and Maxillofacial Radiology.

SHAWNEEN M. GONZALEZ, DDS, MS, is an assistant professor and director of the Oral
and Maxillofacial Radiology Clinic in the College of Dentistry at the University of Nebraska Medical
Center in Lincoln. She is also the creator of an informational website (drgstoothpix.com), where
she educates dental professionals around the world about oral radiology.